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8.2.3 1995 Wavelength Calibration Updates

  In early 1995, concerns were raised about the accuracy of the extrapolations of the low-dispersion wavelength calibrations (i.e., the time and THDA wavelength and spatial zeropoint dependencies) to times beyond the original database of observations. While no errors due to the extrapolated corrections were seen in NEWSIPS data, the IUE Project felt that updating the old wavelength calibration analysis would result in more accurate wavelengths for recent LWP and SWP images. As a result of these concerns, the LWP and SWP wavelength calibration analysis was updated in 1995 using data taken though the beginning of 1995. These new corrections were applied to post-01 January 1990 images while the old corrections were used for pre-1990 images. No calibration update was required for the LWR camera, as it comprised a closed data set. The updated coefficients are listed in Table 8.4.
 
 
Table 8.2:  LWP and SWP Low-Dispersion Time and THDA Coefficients (pre-1990)
  LWP SWP
A1 (Å) 1711.6597 1032.4392
A2 (Å/pix) 2.6626680 1.6763376
B1 (pix) 23.61 21.97
     
W$_{1\lambda}$ 4.4345033 -2.3252555
W$_{2\lambda}$ 4.0537516e-4 3.5285037e-3
W$_{3\lambda}$ -6.0635105e-1 -2.6882430e-1
W$_{4\lambda}$ 0.0 -6.1677609e-7
W$_{5\lambda}$ 0.0 4.2678509e-11
     
W1s -4.3763553 4.3991865
W2s 2.8160580e-4 -3.2833262e-3
W3s 3.6686645e-1 -1.0900706e-1
W4s 0.0 8.2522805e-7
W5s 0.0 -7.1718122e-11


 
 
Table 8.3:  LWR Low-Dispersion Time and THDA Coefficients
  LWR ITF A LWR ITF B
  Pre-1980.1 Post-1980.1 Pre-1979.9 Post-1979.9
A1 (Å) 1730.1170 1730.7719 1727.5143 1728.2415
A2 (Å/pix) 2.6658213 2.6657266 2.6692838 2.6688933
B1 (pix) 24.78 24.78 25.04 25.04
         
W$_{1\lambda}$ 10.1020149 -4.7995158e-1 9.2690908 -2.0569484e-1
W$_{2\lambda}$ -1.6612805e-2 2.9549095e-3 -1.5753037e-2 2.5944874e-3
W$_{3\lambda}$ -4.5748750e-1 -2.4267995e-1 -4.1245027e-1 -2.2761587e-1
W$_{4\lambda}$ 1.6308716e-5 -6.2727972e-7 1.5803093e-5 -6.0699193e-7
W$_{5\lambda}$ -4.5832944e-9 4.2171131e-11 -4.5624765e-9 5.1719073e-11
         
W1s -11.6908924 -11.6908924 -11.5273270 -11.5273270
W2s 2.9216646e-3 2.9216646e-3 3.0038018e-3 3.0038018e-3
W3s 6.1467118e-1 6.1467118e-1 5.9936489e-1 5.9936489e-1
W4s -5.9403908e-7 -5.9403908e-7 -6.2260391e-7 -6.2260391e-7
W5s 4.1402462e-11 4.1402462e-11 4.3818172e-11 4.3818172e-11


 
 
Table 8.4:  LWP and SWP Low-Dispersion Time and THDA Coefficients (post-1990)
  LWP SWP
A1 (Å) 1711.7219 1032.7897
A2 (Å/pix) 2.6627994 1.6763867
B1 (pix) 23.66 21.97
     
W$_{1\lambda}$ 3.1902447 -2.6142797
W$_{2\lambda}$ 1.2511673e-3 3.4473210e-3
W$_{3\lambda}$ -6.2114623e-1 -2.7509139e-1
W$_{4\lambda}$ -1.2237954e-7 -5.6468763e-7
W$_{5\lambda}$ 0.0 3.43165905-11
     
W1s -4.4882965 4.6596390
W2s 2.7621062e-4 -3.2043927e-3
W3s 3.7540199e-1 -1.1149894e-1
W4s 0.0 8.0137016e-7
W5s 0.0 -7.1156480e-11

Figure 8.2:  Low-dispersion time and temperature correlations with wavelength and spatial zeropoints for the LWP camera.

Figure 8.3:  Low-dispersion time and temperature correlations with wavelength and spatial zeropoints for the LWR camera (ITF A).

Figure 8.4:  Low-dispersion time and temperature correlations with wavelength and spatial zeropoints for the LWR camera (ITF B).

Figure 8.5:  Low-dispersion time and temperature correlations with wavelength and spatial zeropoints for the SWP camera.

next up previous contents
Next: 8.3 High-Dispersion Wavelength Calibration Up: 8.2 Low-Dispersion Wavelength Calibration Previous: 8.2.2 Application of the
Karen Levay
12/4/1997